Abstract: A coupling for use in a transmission system and between coaxial rotary members which are arranged for driving engagement through axially engaging teeth thereon, one of said members being connected, directly or indirectly by helical splines to a further part such that in normal rotation, the said one member has a force exerted upon it tending to separate the teeth, such force being resisted by a fusible element which will melt when temperature rises above a predetermined value, melting of said element permitting axial movement of said one member relatively to said further part, through the splines to permit disengagement of the teeth, bearings supporting said further part, being substantially free from axial loading and spring means being provided for preventing re-engagement of the teeth after the element has melted.

Abstract: A coupling for use in a transmission system and between rotary members which are arranged for driving engagement through axially engaging teeth thereon, the teeth being shaped to tend to disengage when normally driving in one direction, one of said members having two components connected by helical splines, the components being prevented from moving axially to disengage the teeth by a fusible element which will melt when temperature rises above a predetermined value, melting of said element permitting movement of the components axially to disengage the teeth and the helical splines permitting axial relative movement between the two components, when reverse rotation is taking place, to permit ratcheting of the teeth.

Abstract: An electric generator arrangement comprises a generator and a continuously-variable ratio drive, whereby the generator can be driven at a constant speed over a range of speeds applied to an input shaft. The drive comprises an epicyclic differential gear having a planet gear carrier driven by the input shaft, a sum gear coupled to coupled to the generator and a ring gear. The ring gear can be driven at varying speeds by hydraulic units to vary the ratio of the speeds of the input shaft and the sun gear. The hydraulic units are driven by the input shaft and the speed of the ring gear is controlled by an electro-hydraulic control system which is responsive to the frequency of an output signal from a part of the generator. Fluid under pressure for the hydraulic units and the hydraulic control system is provided by a combined pump and de-aerator on the shaft of another part of the generator.